1. Field of the Invention
The present invention relates to a display method of displaying a design image obtained from design data and a real pickup image in a superimposing manner.
2. Description of the Related Art
Conventionally, for example, in failure analysis of a large scale integrated circuit (LSI), locations that cause a failure of the LSI (candidates for a logical failure) are logically narrowed down using a failure simulator or the like. Then, the names of the candidates for the logical failure are retrieved and displayed using a layout viewer or the like, whereby the candidates for the logical failure are checked in the layout thereof.
When an LSI has a physical abnormality, failure locations can be physically narrowed down using an analysis device such as an emission microscope, an optical beam induced resistance change (OBIRCH) analysis device, a field ion beam (FIB) device, or a secondary electron microscopic (SEM) device. For example, the emission microscope is capable of acquiring an image on which heated locations are detected, whereas the OBIRCH analysis device is capable of acquiring an image on which OBIRCH reaction is detected. The SEM device and the FIB device are capable of acquiring a real image of the LSI.
When it is found that a physical abnormality discovered by the analysis device has caused a logical abnormality, the discovered physical abnormality can be determined as a cause of the failure of the LSI. Accordingly, if the layout image (design image) displaying the candidates for the logical failure and the analysis image (pickup image) obtained by the analysis device can be easily superimposed over each other, it becomes easy to specify a location of the failure. For example, JP 10-163283 A describes position alignment between a layout image and an analysis image obtained by an analysis device such as an electron beam tester.
The following analyses are given by the present invention.
When an analysis image (pickup image) is displayed and analyzed, the analysis image is sometimes distorted compared to the real image, like in a case in which the analysis image cannot be acquired from a direction vertical to the LSI, or in a case in which the image becomes blurry when photographed. Thus, there occurs a case in which the position alignment cannot be performed sufficiently with the method described in JP 10-163283 A. As an LSI becomes finer, it becomes more difficult to specify the location of a failure due to finer position displacement.